Car Hacking: NXP Pushes Flexible Security

The reality is that, while cars have a number of vulnerabilities, the security level needed for each might differ.

It's important to increase security against manipulation of the in-car network, but "you must carefully look into what you need to protect," says Besenbruch. Tightened security shouldn't affect performance. You don't want to delay braking, because a system requires that the order to brake be authenticated, he explains.

The right solution should be compatible with existing architecture and systems, according to Besenbruch. "Current hardware platforms and software components should be modified as little as possible."

Against that backdrop, one of the NXP's proposals is to secure "existing and future systems" by "integrating a secure memory area that can only be written to and read with authorized access."

By integrating a trustworthy element, described as "a trust anchor," into security-related ECUs, NXP believes that the security of data can be improved. Trust anchors, in the form of a security microcontroller, are not new. They are already used in credit cards and telephone SIM cards. NXP is one of the clear leaders in that field.

Secure element in ECU architecture

Source: NXP

A security processor today incorporates such functions as a secure memory area, cryptographic co-processors, management of certificates and private keys, and generation of public keys.

By adding to an ECU a security processor (like one based on NXP's A700x product group -- already used in other industrial applications requiring security), combined with an existing car microcontroller, NXP believes it can offer security-related features that include:

Firewall applications for securing the gateway. For this purpose, communications can be authenticated before being passed on to the relevant sub-bus.

Secure storage applications, such as error logs or mileages, which can only be written to by means of authentication.

Secure boot. This ensures that the software of individual ECUs has not been compromised.

Certification of (electronic) replacement parts. Only authorized ECUs can be introduced into the vehicle network.

Registration with external services through protected connections. The secure element provides the access data for VPN and HTTPS connections.

Of course, in order to determine which ECUs need to be equipped with a trust anchor, one needs to first identify functions and applications that need to be protected against car hacking.

Potential attack and manipulation scenarios by hackers, described by Besenbruch during an interview with EE Times, ranged from modification of mileage, unauthorized geolocating, and installation of malicious codes in MP3 files, to eavesdropping on telephone conversations via Bluetooth and tuning chips through the manipulation of electronic control unit software.

Depending on where such functions -- vulnerable to potential attack -- exist in the in-car network architecture, a secure element should be offered to locally protect those functions, "by saving, calling or authenticating data used by the ECU's main microcontroller, or securing a connection with additional ECUs," explained Besenbruch.

Also, "a secure boot algorithm that prevents manipulation of the software should be implemented in all cases."

Another weak link: the supply chain There's another aspect to automotive security that the industry shouldn't forget, notes Besenbruch. The supply chain could be the weak link.

Management and the chain of custody of keys and secrets for the installed ECUs during module production are critical. Auto companies must specify which partners install the secure element, who installs the keys in the ECU, and how the allocation is managed at every phase in the distribution chain, according to Besenbruch.

Here, NXP maintains that the company's experience in proven procedures from bank and credit card supply chains can be leveraged for use in automotive production.

Editor's note: EE Times's Automotive Designline is examining how the automotive industry and chip suppliers are planning to address automotive security.
This is the second installment. The first article, How Hackers Can Take Control of Your Car, appeared on July 8.

I came across an interesting company recently that may offer a solution - albeit a bit extreme - for securing that automotive IC supply chain, Junko, particular in the context of the MCU.

I was talking with Olek Cymbalski, owner of OPC Technologies (www.opct.com). He described their service which secures the supply chain by taking in the MCUs to be used in a particular design, programming them here in the US using the required code, removing the ability to recode (securing them) then shipping them to the production line -- anywhere in the world. This, according to Cymbalski, takes the programming details out of the engineers hands, while at the same time ensuring the ICs aren't tampered with along the way from the MCU manufacturer to the production line.

There aren't many ways someone could connect to your car... actually, none. The only way to hack your car is if you do it yourself or have someone do it for you since you would have to physically modify it. It looks like the real issue here is that the car companies don't want you to be able to make modifications to your car. Reminds me of when I was waiting for some friends after work at a brew pub in Austin in 1999. It was crowded and some women offered to share their table with me. One of them was explaining that she quit her job and started a company to fix the year 2000 issue with cars. She was convinced that cars would stop working on 1/1/2000. She said it was the microcontrollers. I was a design manager for microcontrollers in the automotive division at the time. I told her that there was only one microcontoller in the car that knew what time it was and it didn't know if it was am or pm much less what year it was. She wouldn't listen to me so I moved to another table. I wonder how her company did.

I've read the Savage report you mentioned with a lot of interest as it's my job to design such electronics. I designed one of the first MP3 player for car radio in Europe (OEM and aftersale). I can tell you the type of attack (MP3 buffer overvlow) mentioned in the report is just impossible in that case as the MP3 decoder was hardware. I guess it's possible to do a buffer overflow with a software MP3 decoder but I seriously doubt that it could be used to hack the car itself (maybe the car radio alone, even that would be quite time consuming for poor impact). Was there a real demo of what they could do on an unmodified car with this type of attack ?

What makes me think it's impossible to hack a car from the car radio is: The only network beetween the car radio and the rest of the car controllers is the CAN bus, often through gateways (the body network is physically independent of the engine network). CAN reliability is based on hardware message filtering, this way a controller cannot be overflown by a CAN bus. It's part of the validation process of all good designed controllers to check that it cannot crash because of a CAN bus overflow, not be cause of the fear of hacker's attack but more because of the fact that a controller could go crazy on the bus and overflow it (This kind of bug already happened if real life).

Today I design engine and body controllers for different car manufacturers, we do have security schemes in the bootloaders since about 10 years or more. It's mostly based on encrypted keys to allow calibration changes (it's easy to do a BO attack with a calibration change) and updated software download. There are also CRC checks and stuff like that (not talking about key(less) authentification). I know some people could go around these, mostly because of the weakest link: the garages. We need to have the possibility to update the software for the most important controllers of the car, it's a requirement of the car makers. These updates are done in the car repair stations of the brand and these will always remain the weakest link.

The solution to make the controller chip non reprogrammable (mentioned by Patrick) is not applicable in that case. For the controllers that don't need reprogrammability, we just use OTP (One Time Programmable) microcontrollers wich are cheaper thant Flash µC and physically impossible to recode.

Junko, good for you and EETimes to surface these issues. I have to say, it is so scary to read the comments by some (I am assuming by the fact they are at the EETimes web site) knowledgeable and educated engineers on this article and your other one:

The ones I refer to are those that are in total denial that cars being developed today are hackable and/or make the arguments that that if the car is hackable, why go to the trouble, just run into it or cut the brake line....

Are none of these engineers aware or following the massive outcry about the security holes in our existing infrustructures? Have they not followed STUXNET ?

Very sad and scary! Shows how much education or quick retirement needs to be done NOW.

But here's the thing. I have been told that there are instances that users try to modify their own cars (or in the case of car sharing, shared cars) to change mileage, Some people also change engine parameters (say, manupilate it from 100 horse power to 120 horse power engine).

Such manipulation on engine parameterscan be done by software, according to my source. And such actions could directly affect reliability of a car, for example.

Yes, that makes sense. The automotive companies have always worried about their vehicles being modified. They have made it harder for us to work on our own cars. Making a modification should void the warranty, but they worry about the liability if something happens due to the modification.